Ah now I see what you mean by "consistent with the rest of the project" -- I see that methods phone code and postal code related use lower-cased ISO 3166-1 alpha-2 codes.

I'll make it so all ISO 3166-1 alpha-2 codes are downcased before they are stored or compared.

(If there weren't consistency concerns, I think upper-case country codes would be preferable -- official references all use uppercase codes:

They are uppercase in references on iso.org:
http://www.iso.org/iso/country_codes/iso_3166_code_lists/country_names_and_code_elements.htm
http://www.iso.org/iso/home/standards/country_codes/iso-3166-1_decoding_table.htm

They are uppercase in CLDR itself:
# grep 'territory' vendor/cldr/common/main/en.xml
...
                        <territory type="KE">Kenya</territory>
                        <territory type="KG">Kyrgyzstan</territory>
                        <territory type="KH">Cambodia</territory>
                        <territory type="KI">Kiribati</territory>
                        <territory type="KM">Comoros</territory>
                        <territory type="KN">Saint Kitts and Nevis</territory>
                        <territory type="KP">North Korea</territory>
                        <territory type="KR">South Korea</territory>
...)